Impact of enhancing GP access to diagnostic imaging: A scoping review

Background Direct access to diagnostic imaging in General Practice provides an avenue to reduce referrals to hospital-based specialities and emergency departments, and to ensure timely diagnosis. Enhanced GP access to radiology imaging could potentially reduce hospital referrals, hospital admissions, enhance patient care, and improve disease outcomes. This scoping review aims to demonstrate the value of direct access to diagnostic imaging in General Practice and how it has impacted on healthcare delivery and patient care. Methods A search was conducted of ‘PubMed’, ‘Cochrane Library’, ‘Embase’ and ‘Google Scholar’ for papers published between 2012–2022 using Arksey and O’Malley’s scoping review framework. The search process was guided by the PRISMA extension for Scoping Reviews checklist (PRISMA-ScR). Results Twenty-three papers were included. The studies spanned numerous geographical locations (most commonly UK, Denmark, and Netherlands), encompassing several study designs (most commonly cohort studies, randomised controlled trials and observational studies), and a range of populations and sample sizes. Key outcomes reported included the level of access to imaging serves, the feasibility and cost effectiveness of direct access interventions, GP and patient satisfaction with direct access initiatives, and intervention related scan waiting times and referral process. Conclusion Direct access to imaging for GPs can have many benefits for healthcare service delivery, patient care, and the wider healthcare ecosystem. GP focused direct access initiatives should therefore be considered as a desirable and viable health policy directive. Further research is needed to more closely examine the impacts that access to imaging studies have on health system operations, especially those in General Practice. Research examining the impacts of access to multiple imaging modalities is also warranted.

Introduction Diagnostic imaging is vital in diagnosing and monitoring a wide spectrum of disease [1]. High demand on imaging services across the healthcare system poses intense pressure on limited diagnostic imaging resources. Research indicates that direct GP access to diagnostic imaging provides an avenue to timelier diagnosis, a consequent reduction in referrals to hospital-based specialists and emergency departments (ED) [2], and improved quality of patient care and disease outcomes [3,4]. However, GPs' current ability to diagnose and treat public patients within General Practice is often limited by inadequate access to diagnostics that are frequently more readily available in hospital settings [2].
For example, in the Republic of Ireland (RoI), General Practitioners (GPs) are the first port of call for most medical problems and serve as the gateway through which patients access diagnostics and referral to hospital-based specialists. The RoI is unusual in Europe in that 42% of the population are eligible for free GP care [5] while the remainder of the population must pay for GP services. With limited options available for many public patients, GPs have previously been faced with patients requiring a certain imaging study (e.g., MRI or CT), yet such studies could only be organised by ED or other hospital-based specialists, which often caused delays. Therefore, enhanced access to diagnostics for public patients within General Practice, as has been facilitated via a number of Irish policy initiatives in recent years (see Table 1), has allowed GPs in Ireland to manage patients that would otherwise be referred to ED or outpatient clinics, thus, at least in theory, leading to reduced hospital referrals and/or admissions [6].
But limited resources and growing healthcare needs are a major concern, not only in Ireland, but also internationally. Indeed, workforce and workload challenges facing General Practice are well documented in the UK, the EU and further afield [12]. Furthermore, current evidence on the effects of improved access to diagnostic imaging in Primary Care is mixed. Some studies show that direct access is cost effective, timelier, and adept at identifying patient health problems [13,14], while others state that direct access to imaging in primary care yields little to no benefit in terms of clinical or resource-based outcomes [15,16]. The purpose of this scoping review is to provide clarity on this matter. The study will aim to do so by conducting Table 1. Direct access to diagnostic imaging in general practice schemes in Ireland. [7] an inductive exploratory investigation of the current literature that demonstrates the value of, or lack thereof, enhanced direct access to diagnostic imaging in General Practice.

Methods
A scoping review methodology was chosen to acquire a comprehensive overview of the literature regarding the value of enhanced access to diagnostic imaging in General Practice. Scoping review methods facilitate broad mapping of the literature, and they provide opportunity to identify key concepts and pertinent knowledge gaps. The scoping review framework used in this review consists of a six-stage process described by Arksey and O'Malley [17] with later recommendations by Levac et al [18]. A study protocol was not produced for this review.

Stage 1: Identifying the research question
This scoping review aimed to determine the value of direct GP access to diagnostic imaging investigations. The following research question was formulated:

Stage 3: Selecting studies
Titles and abstracts of identified studies were read by two reviewers (AP & JB) from the 13 th -15 th and 20 th -21st June 2022 respectively, and those deemed relevant to the study were selected for full-text review. Full text reviewing was conducted by one reviewer (AP) from the 22 nd -27 th June 2022. The PRISMA Extension for Scoping Reviews (PRISMA ScR) flow diagram outlines the study selection process (Fig 1). Consistent with the scoping review methodology, inclusion criteria were broad to include a range of articles. Both peer-reviewed and grey literature were included. Literature was included irrespective of study design or methodology, resulting in various study types being included in the search. Once the initial search was performed, duplicates were removed, and studies were then included and excluded based on criteria described in Table 2.

Stage 4: Charting the data
Once all relevant articles were identified, data were extrapolated and charted by one researcher to facilitate characterisation and thematic analysis of included studies. The following data was charted, as shown in

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Impact of enhancing GP access to diagnostic imaging: A scoping review

Stage 5: Collating, summarising, and reporting results
Data were collated, presented, and reported in the results section (see Table 3). Following this, major themes of the literature were identified using Braun and Clark's 'Thematic Analysis' approach [19]. The Thematic Analysis method facilitates a systematic and thus replicable approach to the coding, synthesis, and interpretation of qualitative data. Whilst Thematic Analysis is mostly used to analyse interview data, the method also provides a useful framework for analysing non-interview qualitative data such as that reported in scholarly articles. The method entails completion of six stages, these being (1) familiarisation with data, (2) initial code generation, the (3) searching for, (4) reviewing of, and (5) defining of themes, and (6) report writing. No assessment of methodological quality was performed. Efforts to establish the value of enhanced access to diagnostic imaging were guided by the Donabedian model for establishing quality of care, with the structure, process and outcomes of such enhanced access initiatives being examined [20].

Stage 6: Consultation
In line with Levac et al.'s recommendations [18], experts in the field of General Practice were consulted to offer support with regards to the study's aims and conduct. Consulted personnel assisted with decision making around choices whether certain studies were to be included and excluded for review and interpretation of study findings. For this review, select GPs from the Irish College of General Practitioners and the University College Dublin / Ireland East Hospital Group GP Research Network were consulted on an ongoing basis throughout June to September 2022.

Search results
Initial searches of the PubMed, Embase and Cochrane Library databases yielded 850 records published since 2012, with an additional 17 identified from hand searches. Following duplicate removal and reviewing of titles and abstracts, 113 were deemed relevant to the review and subject to full-text review. The search, identification and selection process are summarised in the PRISMA ScR diagram (Fig 1). Following this, 23 relevant papers were selected for final inclusion (Table 3).
The sample sizes of the studies ranged from 163 to 1,739,422 participants. Participants' ages ranged across studies. All included studies examined populations over 16 years old.

Interventions studied
A key element across all studies was the implementation of access to external diagnostic imaging services through direct GP referral. The structure of the referral process varied between studies depending on the healthcare system involved and the nature of established access pathways. Most studies involved direct referral to imaging within an external radiology department, independent of hospital-based specialist involvement or additional testing [13, 21-34, 36, 39, 40]. In conjunction with enhanced access for GPs, two studies involved educational seminars for GPs on disease diagnosis and management [27,29].

Outcome measures
A range of outcomes were examined across included studies. One study assessed the feasibility of implementing a direct access pathway [40]. Another analysed utilisation of an established direct access pathway [29]. The cost effectiveness of direct access to diagnostic imaging was explored in four studies [13,21,23,34]. Both GP and patient satisfaction with direct access referral pathways were examined in four studies [3,13,30,32]. Time between GP referral to scan was assessed in three studies [21,27,32]. Of these, one study also examined time spent by patients at a scan through direct access referral [32]. Another study analysed times spent with hospital-based specialists due to a direct access CT pathway (30). Referral to EDs was examined in two studies [33,37]. Four studies examined the appropriateness of such referrals [22,25,30,37]. Current direct access to diagnostic imaging services. There was a consensus across studies that access to imaging services remained limited and varied widely across populations [6,35,36,38]. In one study examining GPs and out-of-hours practices adjacent to hospital EDs, access to imaging was not shown to improve for out-of-hours services located adjacent to EDs, contrary to the study's expectations [35]. In Ireland, direct access to imaging differed considerably between public and private systems. This difference was accompanied by longer imaging study waiting times throughout the public system [6], regardless of whether the study was ordered by a GP or a hospital-based doctor. In the UK, those with direct access to imaging could not access such services within NICE recommended timescales [38].
Cost-effectiveness. Numerous studies found that direct access referral pathways for diagnostic imaging through General Practice are cost-effective, with more timely diagnosis and earlier treatment for patients being shown to further reduce overall costs within the healthcare system [13,21,34]. This was in part due to better use of hospital/radiology resources or reduced hospital admissions. No studies mentioned additional costs in terms of GP resources required to arrange and follow up on direct access imaging studies. One study determined direct ECHO access to be cost-effective with regards to triaging patients with suspected heart disease [23]. Another study showed that direct X-ray access in General Practice can serve as a cost-effective screening method for lung cancer in smokers [34]. Patient satisfaction. It was found that patient satisfaction with diagnostic imaging services as part of diagnosis or management of their condition had increased with direct access through General Practice. Improved patient satisfaction was linked with reduced scan waiting times and referrals to hospital-based specialists facilitated by these interventions [3,30,32]. One study showed that alongside increased satisfaction, patients felt that they were taken seriously and had confidence in the expertise of those providing the services [32]. When compared to a control group with direct referral to a hospital-based specialist, patient satisfaction was lower than the control group, with the controls feeling more informed about their condition as a result of increased time spent with clinical staff [13]. In contrast, another study showed that most patients were satisfied with direct access to diagnostic imaging services and did not feel it necessary to see a hospital-based specialist prior to referral for testing [3].
GP satisfaction. GP satisfaction was explored in one study, showing increased satisfaction because of direct access to imaging, which GPs felt was both useful in diagnosis and cost-effective. The additional workload and opportunity costs that the intervention placed on GP services was not mentioned when examining GP satisfaction [3].
Feasibility and utilisation of intervention. One study explored the feasibility of a direct access transvaginal US pathway for early detection of ovarian cancer in General Practice [40]. The study revealed that such a pathway would be feasible. Eighty percent of patients were managed in Primary Care with the remaining 20% referred for further testing and visitation to a hospital-based specialist. Another study assessed the utilisation of a direct access CT pathway to diagnose lung cancer by GPs [29]. This study showed that two-thirds of GPs used the pathway once it was established. The reasons for lack of use by the remaining GPs were not examined.
Appropriateness of referrals by GPs. By comparing referral patterns to subsequent findings on scans, several studies determined that GPs appropriately referred patients through direct access referral pathways [22,25,30,37]. In one study, referrals from GPs and hospital outpatient departments yielded similar rates of positive diagnostic outcomes [37]. Further, GP direct access testing for symptoms that could indicate cancer has previously been criticised for increasing testing and decreasing diagnostic yield, but a systematic review examining this did not support these concerns [3]. This review reported that no significant difference was found in the cancer conversion rate between GP direct access and specialist testing pathways.
Referral to hospital-based specialists and the emergency department. Both studies examining referrals to emergency departments showed a significant reduction in the number of patients referred to the ED following introduction of direct access referral pathways [33,37]. Another study investigating referrals to hospital-based specialists highlighted that direct access to MRI in General Practice reduced the overall number of referrals to an orthopaedic surgeon in secondary care [31].

Key findings
This scoping review's findings indicate that enhanced direct access to diagnostic imaging services within General Practice is a welcome, feasible, and with respect to health systems in their totality, a cost-effective measure that can often improve both system level and individual patient clinical outcomes (e.g., GP and patient satisfaction, scan waiting times, metrics illustrating referral processes). Both patients and clinicians have expressed satisfaction with direct access to imaging initiatives, particularly with regards to these interventions' positive impacts on waiting times for scans and referrals, diagnostic capacity, and clinical resource management. The level of GP and patient engagement with direct access interventions in the studies examined was often high, indicating that diagnostic imaging interventions are well regarded by both patients and clinicians. The reviewed studies demonstrate that when supported with direct access, GP imaging referrals are generally appropriate, yielding high rates of positive diagnostic outcomes. Although, it should be acknowledged that appropriateness can be wideranging and multi-faceted in its meaning, and there is ongoing work to establish how best to appraise diagnostic imaging initiatives [42].
The findings also show that direct access to imaging can ensure more efficient use of technical and staff imaging resources, reduced hospital admissions, more timely diagnosis / earlier treatment for patients, and reduced overall costs within the health system. However, it is notable that much of the research examined focuses primarily on how direct access interventions impact on the health system at large and on hospital services. It is less clear how access to diagnostic imaging interventions impact on resources and costs specific to General Practice operations. It was also evident that most studies focused on the impacts of modality specific imaging with specific patient populations, that studies usually examined experimental direct access interventions rather than established frameworks, and that research comparing the accomplishments of direct access initiatives in public and private health systems, and across time, is lacking. Most studies included in this review documented direct access initiatives that were based in primarily state subsidised systems, and that were at a relatively early stage of implementation.

Comparisons with existing literature
The World Health Organisation's overview of integrated care models describes communitybased diagnostic imaging services as key to shifting the provision of care from acute to community settings [43]. Key Irish and international policy reports regarding direct imaging access initiatives for GPs share similar sentiments [7,10,12,44]. This review's findings suggest that implementation of such initiatives is likely to have positive effects due to speedier diagnosis in the community and a more balanced sharing of responsibilities within the health system. This may in turn ease pressure on secondary care resources, and with respect to the Irish context in particular, it may contribute to reducing public outpatient waiting times. Further, in a 2015 survey, Irish GPs held that diagnostic imaging would improve patient care across a range of clinical scenarios [6]. This review's findings suggest that GPs accurately predicted the impact of such an initiative, especially with regards to the positive impacts on outpatient referrals and hospital admissions. Of course, not all researchers have communicated such positive views on enhanced GP access to imaging. For instance, Karel et al. (2015) contend that GP imaging referrals for knee and low back pain have ". . .little to no benefit" [15], while Sajid et al. (2020) claim that 'unfettered" GP access to imaging is conducive to mass wastage of service resource and therefore potentially harmful to patient health [16].

Implications for future research and policy
This study's findings indicate that direct GP access to imaging can yield many benefits, particularly with regards to increased satisfaction levels amongst patients and doctors, reduced waiting times and referrals, feasibility of implementation, and cost-effectiveness within health systems at large. However, as mentioned, there is comparatively little research focusing on the impact that direct access initiatives have on General Practice workload and resources specifically, and future research regarding this issue is needed. Other important avenues for future research include examining the effects of direct access to imaging in general rather than with regards to condition specific patient populations. Furthermore, valuable insights may be gained by evaluating existing diagnostic imaging pathways rather than shorter-term experimental pathways constructed solely for the purpose of research investigations. These findings indicate that health systems should continue to support diagnostic imaging pathways within Primary Care, for the benefit of patients, clinicians, and the overall health system. However, to make such initiatives sustainable, policymakers must also consider the opportunity cost of increased imaging responsibilities within General Practice, namely increased burden on already strained GP resources. Ageing populations and GP recruitment challenges have led to a steadily increasing GP workload in recent years, and displacement of other work by such initiatives may occur. As to whether this leads to unintended consequences, separate to effects of the imaging initiatives themselves, must be carefully assessed.

Methodological considerations and limitations
The adoption of a scoping review methodology benefitted this study as the method permitted mapping of the literature concerning direct access to diagnostic imaging within Primary Care and General Practice settings, thus allowing us to provide a clear overview of a research topic that has not been widely investigated. Arksey and O'Malley's scoping review framework ensured that our research development, study selection, and data interpretation processes were conducted using an accepted and rigorous approach. There were some limitations to our review which should be considered. For instance, unlike a systematic review, a scoping review does not include an assessment of study quality as the focus is on covering the range of work that informs the topic rather than limiting the work to studies that meet pre-specified standards of scientific rigour. Further, only articles written in English and published in the last ten years on four electronic databases were considered for this review which may have resulted in the exclusion of relevant studies. For instance, all included studies were based in European countries and so understanding of direct GP access initiatives in non-European contexts remains a significant knowledge gap worth investigating in future research. Notwithstanding these limitations, the 23 studies included allowed us to gain a comprehensive overview of the current literature, identify research gaps, and inform future research on this topic.

Conclusion
This study's findings suggest that direct access to diagnostic imaging services in General Practice may bring many advantages across the healthcare ecosystem. Going forward, health policy should seek to maximise the potential that direct access to imaging in communities can have for population health. Nonetheless, policymakers should also appreciate that continued research in this area, especially that which clearly delineates the various common imaging modalities and their outcomes, in addition to GP and patient perspectives, is required on an ongoing basis. Lastly, with respect to the Irish context, this study's findings indicate that reversion to previous pathways of imaging through hospital-based doctor referral will only lead to further delays in public healthcare, which is at odds with the stated aims of our health system's directives under Sláintecare.